computed tomography (CT)

Sometimes referred to as CAT scan (computerized axial tomography).

Imaging anatomical information from a cross-sectional plane of the body. Each image is generated by a computer synthesis of x-ray data obtained in many different directions in a given plane.

Developed in 1967 by British engineer Godfrey Hounsfield, CT revolutionized diagnostic medicine. Hounsfield linked x-ray sensors to a computer and worked out a mathematical technique called algebraic reconstruction for assembling images from data. In 1973, the Mayo Clinic began operating the first machine in the U.S. Early machines yielded digital images with at least 100 times the clarity of normal x-rays. Over time, the speed and accuracy of machines improved many times over. CT scans reveal both bone and soft tissues, including organs, muscles, and tumors. Image tones can be adjusted to highlight tissues of similar density, and the data from multiple cross-sections can be assembled into 3-D images. CT aids diagnosis and surgery or other treatment, including radiation therapy, in which effective dosage depends on the precise density, size, and location of a tumor.